New Castle County property tax appeals
The 2026 deadline was Saturday, March 14 and has passed. The next window opens in 2027.
Delaware reassesses every 5 years, countywide, on each county's schedule. If you received a reassessment notice this cycle, your deadline runs from the date on it.
Appeals go to New Castle County Board of Assessment Review.
Delaware assesses your home at fair market value as of a recent reassessment base year, and you can appeal every year. An appeal makes sense when recent sales near the base year show your assessed value is too high. It usually will not help if your bill rose only because the tax rate went up.
- Your assessed value is above what your home would have sold for around the county's base year date. Recent comparable sales are your best evidence.
- A recent reassessment set your value too high for your home's size, condition, or location.
- All three counties reassessed recently, so more homes than usual may be off in the first years.
- Your bill went up but your assessed value is fair. A higher bill often comes from the tax rate, not the assessment.
- You are unhappy with the total tax with no evidence the value is too high. The Board reviews value, not the size of the bill.
Read the full explanation
In Delaware, your home is assessed at its fair market value as of your county's reassessment base year. If you think that value is too high, you can appeal to your county's Board of Assessment Review, and Delaware law requires the counties to let owners appeal every year. All three counties recently completed court ordered reassessments, so the base year is new. An appeal helps when you can show, with recent comparable sales near the base year date, that your assessed value is above what your home would sell for. It usually will not help just because your tax bill went up, since a higher bill can come from the tax rate, not your value. This is general information, not tax advice.
Source: Delaware Code, Title 9, Chapter 83 (property assessment) · checked 2026-07-16. In Florida we run the numbers for you. In Delaware we give you the deadline, where to file, and the rules, verified against official sources.
- 2026 filing deadline:
- Saturday, March 14, 2026. That window has closed for this year.
- Filing window:
- File your appeal by March 14 each year. State law sets the window as prior to March 15; the county's 2026 guide sets the electronic deadline at March 14 at 11:59 pm and requires paper forms to be received, not postmarked, by that date. In 2026 March 14 is a Saturday.
- Where to file:
- New Castle County Board of Assessment Review
- Filing fee:
- Free (the county's appeal guide states all appeals are free)
- Phone:
- 302-395-5520
- County portal:
- www.newcastlede.gov/390/Board-of-Assessment-Review
Verified against official sources, approved 2026-07-16.